There have been many attempts in recent years to produce a commercially acceptable synthetic suede-like product. Such materials have been sought primarily for the manufacture of various garments such as dresses, suits, rainwear, and the like. Natural suede has been used for such purposes, but it is a relatively expensive material and often represents the major portion of the costs of making the garments. Moreover, natural suede has the disadvantage of readily showing dirt or other spots on its surface and therefore requires constant cleaning and brushing to maintain its attractive appearance. Natural suede is also easily stained, and such stains are difficult if not impossible to remove without damaging the original appearance and feel.
Some of the process proposed heretofore for the preparation of synthetic suede are described in U.S. Pat. Nos. 2,835,607; 3,098,263; 3,141,051; 3,190,947; 3,3l16,592; 3,655,497; and 3,705,226. The prior art processes have a number of serious disadvantages; the main problem in most instances being the failure of the synthetic suede product to have properties which are sufficiently similar to natural suede so that the consumer is satisfied. In other instances, the processing procedures are so complicated and involved that the final synthetic product is as expensive, if not more expensive, than natural suede. A number of the prior art processes have the disadvantages of requiring the use of expensive apparatus and/or a large number of processing steps.
U.S. Pat. No. 3,705,226 which pertains to a method for preparing the so-called "Ultrasuede" involves a relatively large number of processing steps, chemical impregnations, and solvent treatments. It would be desirable therefore to have a process available for producing a comparable synthetic suede product which did not require so many processing steps, chemical impregnations, and solvent treatments.
In designing a sueded material for use in apparel, the sine qua non is drapability or flexibility in order to be accepted. It is virtually impossible to make a flexible or drapable product even using a very drapable or flexible fibrous web such as a knitted fabric or a thin woven fabric as a base or substrate, if any coating is applied which strikes through the fibers and locks them into place. This makes the product stiff because the fibers can't move in relation to each other. In recent years successful coating on fabrics which are drapable have been effected by coating a film on a transfer paper and then very gently laying on to the fabric a gelled coat or a solution coat to effect adhesion of only the top layer of the fibers.
The known synthetic suede products generally are prepared by forming a woven or non-woven substrate from fibrous or textile materials; coating said substrate with a solution, plastisol or film of plastic material; and then fiberizing the resulting adherent coating by such conventional means as sueding, brushing, grinding, napping, shearing, etc.
One object of the present invention is to provide an improved process for the manufacture of synthetic suede which avoids disadvantages of the prior art processes.
Another object of the present invention is to provide a continuous process for the simultaneous manufacture of two rolls of synthetic suede by a series of sequential steps that do not include chemical and/or solvent treatments.
A further object of the present invention is to provide an outstanding synthetic suede product having surfaces with outwardly extending, non-tapered fibers and body characteristics having the hand, drape, moderate yield and slow recovery qualities normally associated with genuine leather suede.
These and other objects of the present invention are acheived by the discovery that an improved synthetic suede product can be manufactured in a continuous manner by supplying two separate polyurethane feed materials into the first two nips formed by two rotating, heated cylinders carrying two endless, flexible molding bands provided with a multiplicity of minute molding cavities. These two feed materials are polyurethane films a major portion of which form the outwardly extending fibers when they are forced by the first nips into the molding cavities. The other two feed materials are performed fibrous fabrics or materials such as previously woven, knitted, foamed, non-woven, spun bonded, or spun laced material. The latter feed materials form the base or substrate of the improved suede product of this invention. The latter feed materials and the remainder of the polyurethane films are subject to elevated temperatures and pressures while being passed though a second set of nips. The exposed polyurethane films are in a molten or seim-molten condition and serve as an adhesive or glue to affix the outwardly extending fibers or hairs on both outer surfaces of the two separate bases or substrates.